The invention relates to a rotor, in particular a synchronous reluctance machine which can be operated directly on the electric supply network, wherein the rotor has an axis and the rotor is provided with sheets which are at least partly axially layered, wherein the rotor is designed as a reluctance rotor which has a specified number of rotor poles formed by flux-conducting portions and in particular non-magnetic flux-blocking portions of the individual sheets, wherein the rotor has at least one cage which is made of electric conductors that run in a substantially axial direction and are connected at the end faces of the rotor by respective short-circuit rings.
Furthermore, the invention relates to a synchronous reluctance machine and a method for manufacturing a rotor of a synchronous reluctance machine.
The rotors of rotational dynamo-electric reluctance machines are laminated and anisotropic in construction. Flux-conducting portions and flux-blocking portions are arranged in the contour of the individual sheets for magnetic flux. As a result, the fluxes in the magnetic axes d and q are different. The rotor therefore has pronounced poles. These poles are the result of different inductances being designed in the d and q axis of the rotor. The surfaces of the rotor, for example, have a serrated structure or flux barriers are stamped into the sheets of the rotor.
Thus, for example, U.S. Pat. No. 4,795,936 A1 shows a rotor in which the inductances of the rotor are altered by means of recessing. The center of the d axis is thus provided with magnetically soft material and is available as a flux path. This construction generates different magnetic resistances in the magnetic d and q axis of the rotor, thus forming pronounced poles of the rotor there. The inductance of the d axis is greater than the inductance of the q axis. The magnetic resistances in these axes are therefore also different in design. The difference in the inductance thereof is significant for the torque yield of the reluctance machine. To also be able to start a synchronous reluctance motor on an electric supply network e.g. 400 volts, 50 Hz and directly synchronize it with the mains frequency, a squirrel cage must also be provided in the rotor for a direct start-up.
Thus, for example, US 2006/0108888 A1 shows a rotor with short-circuit rods. The rods are separated by bars of the flux barriers in the sheet of the rotor. Local conductor bars are thus present. However, these bars have a negative effect on the properties of the reluctance rotor as part of the magnetic flux in this region is closed and can no longer contribute to torque formation. This reduces the efficiency as well as the power density of the synchronous reluctance machine.
Likewise, a reluctance rotor with completely filled flux barriers is known from WO 2014/166555 A2. The increased material input increases the inertia and the costs of the rotor. Furthermore, when using a die casting process, external support of the sheet geometry is necessary during the casting process as the tensile strength of the radially external bars of the laminated core may be overloaded during casting as a result of the application of pressure in the flux barriers.